Alkali metal titanates have electrochemical properties which male them desirable as electrode materials for a variety of devices. Lithium titanate (Li4Ti5O12) has been found to have particular utility as an electrode material for lithium batteries. It is a relatively low-cost material, and exhibits high performance characteristics in lithium batteries; consequently, it is anticipated to have significant utility as an electrode material for high performance, high power batteries such as those utilized in hybrid electric vehicles and other high power applications.
One important characteristic of high power, high performance batteries is rate capacity. That is, the rate at which the batteries can take up and deliver an electrical charge. This parameter is particularly important under high charge/discharge rates as are encountered in electric vehicles and other high power applications.
First cycle reversibility is another very important parameter for rechargeable lithium batteries. This parameter measures the decline in storage capacity when a freshly manufactured lithium battery is initially cycled. Manufacturers compensate for this initial loss by building extra capacity into batteries. However, this approach increases the size and cost of batteries, and industry has always sought to limit magnitude of first cycle reversibility.
Various lithium titanate materials are commercially available and are utilized in the manufacture of lithium batteries. However, heretofore available commercial materials produce lithium batteries having first cycle reversibilities of approximately 80%, which represents a significant inefficiency. Furthermore, there is a need to improve the rate capacities of prior art batteries to make them practical for use in high power applications. Clearly, there is a need for improved lithium titanate electrode materials.